1. Field of the Invention
The present invention relates generally to an aircraft engine assembly of the type comprising a turbojet engine, a nacelle surrounding the turbojet engine, as well as an attachment pylon provided with a rigid structure and a plurality of engine mounts placed between a rigid structure of the attachment pylon and the turbojet engine.
The attachment pylon is also called an EMS (“Engine Mounting Structure”) and can be used to suspend the turbojet engine below the aircraft wing, or to mount the turbojet engine above this same wing, or else to mount it to the aft section of the fuselage. It is indeed provided to constitute the connecting interface between the turbojet engine and a given structural portion of the aircraft. It transmits forces generated by the associated turbojet engine to the structure of this aircraft, and it also enables routing of fuel, electrical, hydraulic and air systems between the engine and the aircraft.
The nacelle is conventionally equipped with several cowls surrounding the turbojet engine and providing access to this latter in the open position, these cowls being known under the names fan cowls and thrust reverser cowls.
2. Description of the Related Art
More precisely, certain engine assemblies of the prior art are provided with an attachment pylon having a rigid structure comprising a longitudinal caisson as well as two lateral caissons affixed to the longitudinal caisson and arranged on both sides of the latter, the pylon also comprising means for mounting the turbojet engine onto the rigid structure, these means comprising a first, second, and third front engine mounts for transferring thrust forces to the fan casing. As schematically shown in FIG. 1 showing a prior art embodiment in which the engine is adapted to be suspended under the aircraft wing, the three front engine mounts transferring thrust forces are arranged so that the third front engine mount 8 passes through a diametral plane P1 of the turbojet engine, here the vertical plane of symmetry of the turbojet engine, whereas the first and second engine mounts 6a, 6b, respectively adapted to be connected to the two lateral caissons of the pylon, are arranged on both sides of the diametral plane P1, and usually extend through another diametral plane P2 of the turbojet engine, orthogonal to the aforementioned diametral plane and corresponding here to the horizontal plane of symmetry of the turbojet engine.
Furthermore, the turbojet engine conventionally comprises a fan casing 12, an intermediate casing 21 located radially toward the inside with respect to the fan casing and connected to the latter by means of a plurality of structural arms 17, preferably radially oriented, as well as a central casing 16, also referred to as a “core” casing, extending the intermediate casing 21 toward the rear. Finally, it must be noted that the central casing extends up to a rear end 19 of greater dimension, also called the ejection casing.
As shown in FIG. 2, the engine assembly comprises an annular load-transfer structure 60 surrounding the central casing 16 and mechanically connected to the latter by the intermediary of mounting means 62, conventionally comprising a plurality of connecting rods. As schematically shown by the arrows 76, the annular structure 60 is also connected to a plurality of structures (not shown) arranged externally with respect to the latter, and acting upon it, for example radially, respectively at a plurality of load application points, generally circumferentially distributed on the latter.
Therefore, the annular structure makes it possible to transmit forces between the central casing and the outer structures, whereby the latter can be, for example, the outer radial delimiting structure of the annular bypass air duct (in English “OFS”, Outlet Fan Structure), and/or the inner radial delimiting structure of the annular bypass air duct (in English “IFS”, Inlet Fan Structure).
However, in the solutions of the prior art, the arrangement of the aforementioned connecting rods not being optimized, the passage of forces causes the annular load-transfer structure and/or central casing to deform, which, naturally, is not desirable.